1. Field of the Invention
The present invention relates to fluid filled shock absorber apparatus and more particularly to a new and improved bi-directional flow control device for the damping head assembly of a fluid filled shock absorber apparatus which flow control device is capable of providing variable preloads and variable rate characteristics, as desired, for each direction of movement of the damping head. More particularly, the present invention relates to a fluid filled shock absorber having a cylinder and rod relatively movable therein with a damping head assembly dividing the cylinder into compartments on opposite sides and at least one bidirectional flow control valve mounted in the damping head and communicating with the compartments. The flow control valve provides a new and unique structure whereby variable preloads and displacement rates can be selected for accommodating movement of the damping head in opposite directions in response to predetermined shock forces reacting between the cylinder and rod.
2. Brief Description of the Prior Art
Over the years a wide variety of fluid filled shock absorbing devices and damping assemblies have been developed for damping relative movement between a rod and a fluid filled cylinder supporting the rod for longitudinal displacement. U.S. Pat. Nos. 2,916,281; 3,706,362; 3,896,908, 3,945,474; 4,113,072; and 4,396,098 disclose shock absorbers and damping assemblies as do French Pat. No. 1.018.903 and No. 76 18118 and European patent publication No. 0045268. Through the piston bi-directional relief valves which are responsive to a pressure differential across the piston in either direction are also known.